The purpose of this project is two-fold: (1) to create a realistic model system for exocytosis, with paricular emphasis on tis relevance to transmitter release at synapses; (2) to reconstitute, in lipid bilayer membranes, ion permeability systems existing in biological membranes. The system to be investigated is the interaction phospholipid vesicles with lipid bilayers membranes. The basic questions are: will such vesicles fuse with the bilayer from one side and release their contents on the other side, and at what rate does this occur? What is the effect of lipid composition (both of the vesicles and the membrane) on the rate of this process? How is this rate controlled both by the surface charge of the vesicles and the membrane, and by the concentration of divalent cations (such as Mg ions and Ca ions) in the medium? By first incorporating into the vesicles naturally occuring ion-conducting channels (e.g. the acetylcholine receptor from electroplax), one can then, via the fusion process, incorporated these channels into the bilayer membrane.